Quartz Crucible Coating Profile for Uniform Silicon Pulling Crystallization
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Solution Overview
Problem
Existing quartz glass crucibles used in silicon single crystal pulling face issues with non-uniform crystallization, leading to peeling of crystal layers and dislocation in the silicon single crystal, which can be exacerbated by uneven application of crystallization accelerators.
Innovation Solution
A quartz glass crucible with a specific impurity concentration profile, where the concentration of Fe is higher than Al in the inner surface vicinity, and controlled application of a crystallization accelerator like barium, promotes uniform crystallization in the in-plane direction while suppressing it in the depth direction, forming a thin and uniform crystal layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a crystallization accelerator is applied to the inner surface of the quartz glass crucible to promote crystallization, then the durability of the crucible is improved, but non-uniform crystallization occurs leading to peeling of crystal layers
Solution Approach 1:
The patent applies different concentrations of crystallization accelerators to different regions of the crucible inner surface. Specifically, a first concentration is applied to a first region and a second concentration (different from the first) is applied to a second region. This local variation in accelerator concentration ensures uniform crystallization across the entire inner surface, preventing peeling of crystal layers while maintaining crucible durability.
2Speed
If the concentration of crystallization accelerator is increased to promote uniform crystallization, then the crystallization speed increases, but the crystal layer becomes too thick and peels off
Solution Approach 1:
The patent controls the concentration parameter of the crystallization accelerator to optimize crystallization. By using a specific concentration range (1×10^-6 to 1×10^-3 g/cm²) and varying it across different regions, the patent achieves both fast crystallization speed and appropriate crystal layer thickness, preventing peeling while maintaining high efficiency.
3Reliability
If the inner surface of the crucible is fully crystallized to prevent peeling, then the durability improves, but dislocation occurs in the silicon single crystal
Solution Approach 1:
The patent creates different crystallization states in different regions of the crucible inner surface. By applying different concentrations of crystallization accelerators to different regions, the patent achieves uniform crystallization that prevents peeling while controlling the crystallization extent to avoid dislocation in the silicon single crystal during growth.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach prevents peeling of crystallized portions and reduces dislocation in silicon single crystals, enabling long-duration crystal growth with improved yield and quality.
Implementation Method 1
the inner surface of the crucible base body is uniformly crystallized by heating in the crystal pulling up step
Implementation Method 2
a deposited layer of raw material particles is arc-heated from an inside of a mold to melt the deposited layer
Data Source
AI summary
A quartz glass crucible includes a crucible base body consisting of silica glass and a crystallization accelerator-containing coating film formed on an inner surface of the crucible base body. A concentration of Fe contained in a first depth region of the crystallization accelerator-containing coating film of 0.5 mm or less from an inner surface of the crucible base body is higher than a concentration of Al contained in the first depth region of the crystallization accelerator-containing coating film.